1. Field of the Invention
This invention pertains to the field of reaction motors in which air is supplied by ram effect and in which a mixture of fuel and oxidizer is injected into the reaction zone.
2. Description of the Prior Art
In a well known dump combustor, as used for example in a ramjet, fuel and air mixed insufficiently for combustion flow through a duct having a relatively small cross section upstream of a "dump" at which the flow cross section increases substantially instantaneously generating vortices which thoroughly mix the fuel and air for combustion downstream of the dump. In prior art combustors of this type the cross section upstream of the dump, insofar as is known, is substantially circular resulting in coherent flow downstream of the dump so that such vortices are uniform circumferentially of flow issuing from the smaller diameter section. These vortices, being uniform, form and break away at uniform intervals so that heat release upon mixing by the vortices is periodic with resulting pressure oscillations in the combustor. If these oscillations resonate with other accoustic oscillation natural to the combustor, very high amplitude oscillations result with damage to the combustor, an engine employing it, or the structure of a vehicle provided with the engine. Such high amplitude oscillations may, in any event, perturb a guidance system of the vehicle or expel a desired shock from the inlet of such an engine causing an unstart thereof. As a result the advantages of such a prior art dump combustor, such as simplicity in construction and efficient combustion, are often not practically useable.